The U.S. Supreme Court on Monday rejected a request from a trio of conservation and environmental groups seeking to block construction of President Trump’s wall along the U.S.-Mexico border.

The justices declined to consider the groups’ appeal of a lower court ruling that paved the way for the federal government to begin replacing border fencing in two locations and building wall prototypes.

The judge, U.S. District Judge Gonzalo Curiel, rejected the groups’ challenge to a 1996 federal law that gives the government the power to waive environmental laws to more quickly begin work on a wall. The Department of Homeland Security sought to sidestep the laws as it pursued the projects related to construction of the border wall.